1. Field of the Invention
The present invention relates to a method of and apparatus for welding elongated, flexible members, such as thermoplastic members, into a frame.
2. Description of the Prior Art
Heretofore, frames consisting of elongated, flexible members, such as thermoplastic sealing profiles used on refrigerator doors, have been individually and successively welded at all four corners. In such a method, however, the legs have to be clamped, heated, welded, and unclamped four successive times until the frames are completed. Such a method cannot be carried out automatically and gives a relatively slow rate of production and a consequent high cost for the frame that is produced.
Another known method comprises loading the individual members which form the legs of a frame and then simultaneously and automatically welding the corners to form the frame. However, this method has the disadvantage that the operator, who loads the legs and who then starts the automatic sequence of operations, must wait until the joints have been heated, welded, and cooled before he can remove the frame and initiate a new cycle with the loading of new legs.
It is therefore an object of the present invention to provide a method of and a fixture for simultaneously welding the corners of a frame which avoids the foregoing disadvantages of the prior art methods and fixtures.